It means your amp is staying on. You need to make sure your remote wire is not connected to a constant 12v source. Or it could be a stray wire is in contact and causing it to stay on (had that happen before)
Pretty sure the 901-5 only had minor isotope leakage from the main power transformer to the secondary mosfets. For the most part, harmless... unless the light stays on. I think at that point there was a 50/50 chance or 60/40 chance of gamma exposure causing impotence. But only if it's an eXcelon model.